Rotary hammer



Hi IVI. PLAISTED.

ROAHY HAMMER.

APPLICATION HLED DEc.13,19x9.

Reissued May 25, 1920.

' y IIIIIIIllI-UIIFIIIIIIIII mmm Afro/m r:

tration of UNITED STATES PATENT OFFICE..

` HAROLD M. PLA'ISTED, OF ST. LOUIS., MISSOURI, ASSIGNOR TO WILLIAMS PATENT CBUSHER AND PULVERIZER CO., F ST, LOUIS,1VIISSOURI, A CORPORATION 0F.

' MISSOURI.

ROTARY HAMMER.

Specication of Reissued Letters lfatent. Reissued May 25, 1920,

Original No. 1,281,829, dated October y15, 1918, Serial No.- 237,907, filed June 3, 1918. Application for reissue filed December 13,

i To all whom it may concern.:A

Be it known that I, HAnoLD M. PLAISTED, a citizen of the United States, residing at the city of St. Louis, State of Missouri, have invented certain new and useful Improvements in Rotary Hammers, of which the following s a specification.

This invention relates to certain new and useful improvements in rotary hammers for grinders, pulverizers, and like reducing machincs, the peculiarities of which will be hereinafter described and claimed.

The .main object of my invention is the provision of a rotary hammer of such pivotal mounting and arrangement of adjacent parts, that the operative edges will have effective cage clearance, and will clear adjacent hammers.

In the accompanying drawings on which' like reference letters indicate corresponding parts, Figure 1. represents a partial sectional i elevation 'of any suitable reducing machine,

embodying my invention;A A

'Fiom 2, a horizontal sectional view on the line of Fig. 1, lookingupward;

Fig. 8, a vdetail view of my hammer; and Fig. 4 another form of my kammen The general style .of grinders to which my improvements are'fespe'cially applicable,

is shown in Patent No. 1,266,894, dated rMay 21, 1918, to-whichi reference is made for illusdetail construction not shown herewith. 1

The letter A designates an arcuate cage, concentric with a shaft B on which are keyed disks- CC1-C2-C3, etc.,that carry hammer rods D on which are.pivoted hammers that coperate with said cage' in grinding the material `supplied thereto. YThese hammers each consist preferably of flat bar steel of suitable thickness, the parallel sides E of which constitute a shank. At the outer end of said shank are locatedoperative or cutting edges F-F extending across the thickness ofv the bar and equally distant from a longitudinal central line G, and preferably formed at the extremities of lateral angular projections formedby the out-- wardly diverging sides and a square or-o'ther shaped outer end' I. l These symmetrical 0perative edges may be otherwise formed. The opresite or inner end of said shank is shown in 4igs. l and 3,'.as being widened to sides E that meet a'gsq-uare inner end'K at right 1919. Serial No., 344,674.

side of the line G is farther from the center of the hole L than'is the edge F that is on the same side of the axis as the center of the hole L. When the hammer is mounted on its rod D, and the shaft is rotated in the direction of the arrow, the center of, gravity of the hammer will be normallyl located on a radial line from the shaft B and the hammer will assume substantially the position shown at R and R1. In this normal position of rotation, the forward edge F is in front of the radial line through the center of gravity of the hammen Under the resistance of the material" being ground the forward edge will approach closestv to the cage when itl falls back to this line, as shown at The rear edge F however, on account of Vbeing nearer to the center L, and on the opposite side of the line G, .will be approximately four times farther from'the cage than F, in the position of a hammer shown at R and R1; and this proportion increases when the forward edge of the hammer is forced back under the resistanceof the material being ground. This comparative `location of the front and rear edges brings the forward edge in its coperative position, close to the cage, while it withdraws the rear edge more and more from the material being groundand away from the cage, thus avoiding dulling the rear edge, and also providing clearance for the forward edge.

At R1 is indicated at M and N, the usual f .and maximum wear respectively, before reversing the hammers on the hammer rods so as to bring the edge F to the front as the working edge. This is done by means of a corresponding hole L', theccnter of which (see Fig. 3.) is located on the opposite side of the line G, diagonally from the center of the hole L, and bears a reverse relation to the edges F and F that is borne by the center ofthe hole L; that is, the edge F is a farther distance from L than is the -edge F; the distance between F and L is substanl best suited to reduce the material fed tothe tially the same as between F and L', and the distance F L. is substantially the same as F L. In other words, the hammer pivot holes. the cutting or operative edges, and the side edges of the shank, are all symmetrically located with regard to the central longitudinal line G through the shank. lVhen the edge'F is worn back as mentioned above. andthe hammer is reversed so as to pivot on the center L', the edge F will approximate the position indicatedV at R2 and will practically renew the effective or cutting action of the hammers for a further period.

Fig. 4 shows another form of my hammer, in which the hub width E-,E of Fig. 3 is continued the length of the shank. This avoids forge work at the inner end. Near the outer end are provided corresponding holes L2 vand La-the centers of which hear the same relation to the corner edges F2 and F3 respectively, as L and L bear to the other operative ed es F and F. lVhen the outer edges F an F are successively.

worn down as indicated at M, the hammer-v can be remounted successively to pivot on the centers of the holes L and L3; the co1'- ner edges F2 and F3 will thus become successively the operative edge, and further effective use of said hammer is provided.

The operative edges F-F' are shown in Figs. 3 and 4 asprojecting laterally beyond the Side edges EL-E of the shank, and are equi-distant from the axis G.

' The length of the operative or cutting edge may be the width of the hammer, or may be more or less, according to the shape hammers.

In order to prevent dulling the corners of the opera-tive edges by contact with adjacent hammers, a limit stop for the oscillation of the hammer is provided in both directions, preferably by means of a bearingl edge 2 and a bearing edge 3 formed by cut-out portions of each disk plate at alternate hammer rods, thus forming a pocket in connection w1th a clearance arc 4.V lVhen the hammer' is 1n the position shown by full linesat R and RA', the side edge of the hub width E 1s substantially in contact with the bearing edge 2; at R2, the hammer has receded slightly under resistance of .the material; the dotted position at R1 indicates the side edge E of the hammer being llmlted 1n its backward swing by the bearing edge 3.

The same side `edge of the hammer is in contact with said bearing edges or stops,'

but stop edge 2 acts on side edge E inside the pivot center L, while the stop edge 3 acts on side edge E outside of said pivot, measured radially. T he saine is true when the hammer shown in Fig. 4, is substituted for that of Fig. 3,-only the stop edge 3 is cut back more to correspond to the h ub width of said shank. Being on the same side of the hammer, the stop edges are more tions; that the off-centering of the pivotal ner, or point, is farther away from the cen- Ahaving a pair of holes near the other end accurately located with respect to the actual pivot center or hammer rod.

It will be observed that in the' construction shown in Fig. 4, the hammer possesses ners; that the pivotal points of mounting being locatedto one side of the longitudinal axis, at each end of the hammervenable it'to be used efficiently in four different posipoints, when the hammers are held outwardly by centrifugal. force, causes said hammers to occupy tangential positions, in: which the outer forward reducing edge, corter of revolution (shaft B) than the rearmost outer edge of the hammer, and that to`eifect then above it is necessary to piv' otally mount the hammer inl the rear-most z'. e.'-a=rrange the pivot bolt D through the rearmost hole inthefinner end of the hammer, as shown in Fig. 1the direction of rotation of the hammers being indicated by the arrows.

I claim:

1. A rotary hammer comprising a flat bai shank provided with an operative edge at one end on each 'side of the central line of the shank, and having pivot holes located on opposite sides of said line near the other end.

2. A rotary `hammer comprising a flat bar shank provided with outwardly diverging lateral projections at one end of said shank,

adapted for pivotal mounting.

3. A rotaryy hammer comprlsmg a fiat bar shank provided at each end on opposite sides 1 thereof with operative edges substantially equi-distant from the central line of the shank, and also with a pair of holes near each end of the shank substantially equidistant from the central line, and the center of each hole substantially equi-distant from the operative edge at the opposite endof the shank respectively, measured diagonally across the longitudinal central line of the shank. v

4. A rotary hammer comprising a flat bar shank, provided at one end with operative edges, equi-distant from the central axis of the shank, and at the other end with another pair of operative edges separated l laterally a farther distance than the first pair, saidsh-ank having a pair of holesnear each end thereof, equi-distant from said axis for pivotal mounting, and each hole being equl-distant from the farthest operative edge respectively.

5. The combination with a shaft, a. suitable casng, oscillatable rotary pivoted hammers having sharp edges at front and rear faces and having contact portions on one 1 four cutting or disintegrating points or corhole, considering the direction of rotation-f v face of the shank near the pivot end, of a. set of disks substantially as thick as the hammers having pockets and alternately arranged on said shaft with regard to said poc ets, each of said pockets having two bearing faces located near and at the same side of said pivot, but radially inside and outside the pivot respectively7 so as to effect contact alternately with said contacts on thc adjacent side of the hammer, and limit the oscillation of said hammers in both directions and thereby prevent overlapping and dulling of adjacent hammers.

6. In combination with a cage, a reversible hammer having oppositely disposed cutting edges on one of its ends and pivotal means adapted to be applied Aon each side of the longitudinal axis of said hammer and at the opposite end thereo from said cutting edges, whereby the forward edge will be nearest the cage when said hammer is in operation. a

7. A rotary hammer provided with operativeedges at one end and provided at the other end with openings on opposite sides of the longitudinal centra] line thereof.

8. A rotary hammer having at on end oppositely disposed cutting edges and provided at the other endA with openings on opposite sides of the longitudinal central line thereof.

In testimony whereof, I hereunto aliix my signature, this 1st day of December, 1919.

HAROLD M. PLAISTED. 

